Flexible circuits have been used to carry heat generating components such as integrated circuit chips and power switching applications because the thin flexible circuits can provide a short path to an underlying heat sink. In such systems, "dummy" thermal solder bumps are applied to the chips and soldered to the flexible circuits to provide a heat path from the integrated circuit chip to the flexible circuits. Thermal vias are then provided through the flexible circuits by way of copper through holes to the bottom surface of the flexible circuits. The flexible circuit is then bonded to a heat sink using a thermal adhesive which is a resin filled with thermally connective material. However, the greatest resistance to heat flow in the system that is the thermal adhesive which has a relatively low coefficient of thermal conductivity.
The present invention provides alternatives and advantages over the prior art.